
ul{
    list-style: none;

}

.u1 li{
    float: left;
    border: 1px solid;
    /*border-radius: 10px;*/
    background: gray;
    width: 200px;
    height: 100px;
    text-align: center;
    line-height: 100px;
    margin: 0px;
    position: relative;
}
.u1 li:hover{
    background: green;
}
.u2{
    display: none;
    position: absolute;
    left: -41px;
}
.u1 li:hover .u2{
    display: block;
}

.u2 li:hover{
    background: aliceblue;
}

.u3{
    left: 160px;
    top: 0px;
    position: absolute;
    display: none;
}
.u2 li:hover .u3{
    display: block;
}
.u3 li:hover{
    background: red;
}
